In situ XRD measurements during plasma nitriding of a medium carbon steel

This paper describes a system designed for in situ X-ray diffraction (XRD) analysis during plasma nitriding and gives results of some initial experiments. Besides in situ XRD, the AISI 1045 nitrided samples were analysed by glow discharge optical spectroscopy (GDOS), metallography and hardness tests. The results presented in this paper show that XRD in situ analysis during plasma nitriding can be successfully established. These first tests suggested that, in the long term, a number of important issues of plasma nitriding can be clarified using both in situ XRD measurements together with commonly used post-mortem techniques. Good intensity and resolution were obtained with this equipment, although data collection was time-consuming. The effects of three different gas composition have been confirmed during the nitriding time and temperature applied. The 76% N2-24% H2 gas composition produces thick compound layers and diffusion zones whereas the 5% N2-95% H2 gas composition results in a thin compound layer and thick diffusion zone. The 100% N2 gas composition was found to give almost no nitriding effect.